On Wednesday, November 2, 2016 at 7:37:52 PM UTC-7, Anthony wrote: > > On Wednesday, November 2, 2016 at 7:52:05 PM UTC-4, Dave S wrote: >> >> There are 2 mechanism in HTML5, I believe, but I'm only going to point >> you at one for the moment: Web Workers. >> <URL: >> http://www.htmlgoodies.com/html5/javascript/working-with-web-workers-in-html5-powered-web-pages.html >> > >> <URL: >> http://www.htmlgoodies.com/HTML5/client/introduction-to-html5-web-workers-the-javascript-multi-threading-approach.html >> > >> <URL: >> http://www.htmlgoodies.com/html5/other/html5-tech-shared-web-workers-help-spread-the-news.html >> > >> >> With this mechanism, you'd spawn a web worker to do jquery/ajax to check >> when it was time to replace the content. A couple of the examples >> calculate Pi, and paste the results into the main page. >> > > This approach is "short polling" (i.e., polling the server with quick > requests at some interval to check for updates). Note, there is no > particular reason this must be done with a web worker -- you can simply do > it from the main web page, as it has been done since long before web > workers existed. >
The idea I was applying was keeping the main page quiet, although Google News has used refresh interval to update the entire main page. Web workers give you a thicker curtain to draw over the checkers, than does a LOAD/jquery/ajax in a timer loop on the main page. > The idea is simply to keep making Ajax requests at regular intervals > (e.g., every second). This approach might be fine, though depending on how > many users are connected and how frequently they are checking, the server > could get overwhelmed with requests. To reduce the load, you can decrease > the request frequency, but then you increase the average latency between > when a message is sent and when the recipient receives it. > > >> There is also web sockets in HTML5. >> <URL: >> http://www.htmlgoodies.com/html5/tutorials/making-html5-websockets-work.html >> > >> Gluon/contrib has websocket_messaging.py. >> > > To handle the shortcomings of "short polling", you can instead use > websockets (or long-polling, which maintains a long-held HTTP connection > with the server until a new message is received). However, you need a web > server and application that can handle many long-held open connections. To > address this need, web2py includes websocket_messaging.py, as noted above > -- it makes use of the Tornado web server to handle the websocket > connections. You can also use various realtime messaging services (e.g., > Fanout <https://fanout.io/>), or something like Pushpin > <http://pushpin.org/> (an open source proxy server used by Fanout), which > is probably a bit more robust and full-featured than websocket_messaging.py. > > Anthony > Thanks for the additional pointers. /dps -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
